JP2001051910A - Non-volatile memory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect data just before reloading and to shorten time required for data reloading of a sector even when an accident occurs in the middle of reloading. SOLUTION: This device has a non-volatile memory 1 having plural sectors and capable of electric erasure and write for performing the erasure for the unit of a sector, a non-volatile memory control means 2 for instructing and controlling the erasure, write and read of data to the non-volatile memory 1, a temporary sector data holding means 3 for temporarily holding sector data and a sector managing information holding means 10 for holding sector managing information showing which sector stores effective data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nonvolatile memory device.

[0002]

2. Description of the Related Art There are the following types of conventional nonvolatile memory devices. A non-volatile memory capable of electrically erasing and writing, performing erasing in units of predetermined blocks (hereinafter referred to as a sector, which is a unit of writing and erasing to a flash memory in detail) so that stored data is not lost even when power is turned off; A nonvolatile memory control means is provided for instructing and controlling data erasing, data writing, and data reading to and from the nonvolatile memory.

When reading data, data is read from a specific sector according to the content of the data. When rewriting data, the nonvolatile memory control means reads data from a specific sector (rewriting target sector) corresponding to the content of the data to be rewritten and stores the data in the sector data temporary holding means. After the data to be rewritten is updated and the sector to be rewritten is erased, the updated sector data in the sector data temporary holding means is written to the erased sector to be rewritten.

[0004] A non-volatile memory capable of electrically erasing and writing, performing erasing in units of a predetermined block (hereinafter referred to as a sector) and storing data even when power is turned off, and erasing data, writing data, A nonvolatile memory control means for instructing and controlling data reading and a sector management information holding means for holding sector management information indicating in which sector valid data is stored.

The non-volatile memory has one or more rewrite target sectors (zero or more non-rewrite target sectors) and a spare sector in the same number as the rewrite target sectors and associated with each target sector. ing.

The sector to be rewritten and each spare sector are:
When the contents of the rewrite target sector are rewritten, the contents of the spare sector corresponding to the rewrite target sector are similarly rewritten, and the contents of the rewrite target sector and the corresponding spare sector are written. When the sector to be rewritten is determined to be abnormal with reference to the data verification unit of the sector to be rewritten,
The contents of the spare sector corresponding to the rewrite target sector are copied to the rewrite target sector, and when the spare sector is determined to be abnormal by referring to the data verification unit of the spare sector, the rewrite corresponding to the spare sector is performed. The contents of the target sector are copied to the spare sector.

FIG. 17 is a diagram for explaining the operation of the prior art 1.
Reference numeral 1 denotes a nonvolatile memory such as a flash memory, and the nonvolatile memory includes sectors 0 to 3.
Reference numeral 2 denotes a nonvolatile memory control unit which is connected to the nonvolatile memory 1 and instructs and controls data erasing, data writing, and data reading in the nonvolatile memory 1, and 3 denotes a sector data temporary holding unit for temporarily holding sector data. , For example, a RAM.

Here, when rewriting a part of the contents of the sector 1, the nonvolatile memory control means 2 stores the contents of the sector 1 in R.
Copy to AM3 (). Next, the nonvolatile memory control means erases the sector 1 and rewrites the data to be rewritten in the RAM 3 (). Next, the nonvolatile memory control means 2 writes the contents of the RAM 3 into the sector 1 (). The problem with this method is that if there is an accident on the way, the contents of sector 1 will be lost.

FIG. 18 is an explanatory diagram of verification and return of the prior art 2. The same components as those in FIG. 17 are denoted by the same reference numerals. In this embodiment, all sectors 0 to 3 have spare sectors. The non-volatile memory control means 2 checks the data verification section 1b of the sector 1 and the spare sector for the sector 1 as shown in FIG. In addition,
1a is an actual data section.

Here, the operation of the data verification unit 1b will be described. 1. Method 1 A predetermined bit pattern (for example, 55h) different from the value after erasing (for example, FFh: h indicates a hexadecimal number) is written at a predetermined position (for example, end) of the sector immediately after writing the real data portion. If the predetermined position (for example, the end) of the sector is a predetermined bit pattern (for example, 55h), it can be determined that the writing of the actual data is performed normally.

2. Method 2 In addition, the checksum of the actual data portion 1a is written at a predetermined position in the sector. Read the actual data and checksum,
If there is no inconsistency, the actual data can be determined to be normal.

Consider a case where the data verification unit 1b of the sector 1 is abnormal and the data verification unit 1b of the spare sector for the sector 1 is normal. The non-volatile memory control means 2 copies the contents of the spare sector for sector 1 to the RAM 3 as shown in (b), erases the sector 1 as shown in (c), and
Is written to sector 1 ().

When the data verification section 1b of the sector 1 is normal and the data verification section 1b of the spare sector for the sector 1 is abnormal, the nonvolatile memory control means 2 stores the contents of the sector 1 in the RAM.
3, the spare sector for sector 1 is erased, and R
Write the contents of AM3 to the spare sector for sector 1.

The data verification unit 1b of the sector 1 and the sector 1
When both the data verification units 1b of the spare sectors are normal, nothing is done. When both the data verification unit 1b of the sector 1 and the data verification unit 1b of the spare sector for the sector 1 are abnormal, the data cannot be corrected, but such an accident hardly occurs.

FIG. 19 is an explanatory diagram of sector rewriting of the prior art 2. As shown in FIG.
Copy to M3 (). Next, the sector 1 is erased and the data to be rewritten in the RAM 3 is rewritten as shown in FIG. 1k in the figure is a rewriting portion. Next, the contents of the RAM 3 are written to the sector as shown in FIG. Next, after erasing the spare sector for sector 1, the contents of RAM 3 are changed to sector 1 as shown in FIG.
Write to the reserved spare sector ().

In the case of this method, even if there is an accident between the data, the data immediately before rewriting remains in either the sector 1 or the spare sector. Can be returned to.

The problems are as follows. 1. 1. The same number of spare sectors as rewrite target sectors are required. Since the same data is written to both the rewrite target sector and the spare sector, it takes time to rewrite the data.

[0018]

In the case of the conventional technique, the power is turned off due to an operation error or a power failure, or noise or software bugs occur between the start of erasure of the sector to be rewritten and the completion of writing the updated contents. If the nonvolatile memory control means 2 malfunctions, the contents of the sector to be rewritten are lost and cannot be restored. In order to solve such a problem, in the case of a method of providing the same number of spare sectors as the rewrite target sector, many sectors (that is, memory capacity) are required, and the same data is used as the rewrite target sector. There is a problem that it takes time to rewrite data because data is written to both of the spare sectors.

The present invention has been made in view of such a problem, and can protect data immediately before rewriting even if an accident occurs during rewriting, and can reduce the time required for rewriting data in a sector. It is an object to provide a nonvolatile memory device which can be shortened.

[0020]

According to a first aspect of the present invention, there is provided a nonvolatile memory capable of electrically erasing and writing data having a plurality of sectors and performing erasing in sector units. Non-volatile memory control means for instructing and controlling data erasing, data writing, and data reading in the non-volatile memory, sector data temporary holding means for temporarily storing sector data, and in which sector valid data is stored And a sector management information holding means for holding sector management information indicating the following.

With this configuration, sector rewriting is performed while determining a spare sector with reference to the sector management information holding means, so that even if an accident occurs during rewriting, data immediately before rewriting can be protected. . Also, since only at least one spare sector needs to be provided, the time required for rewriting can be reduced.

(2) In claim 2, the non-volatile memory includes at least one valid sector for storing valid data,
Consisting of at least one spare sector that does not store valid data, each valid sector and each spare sector are:
When reading data, the nonvolatile memory control means refers to the sector management information held in the sector management information holding means to determine which data is desired. When reading and rewriting data by judging whether or not the data is in a sector, the nonvolatile memory control means erases the spare sector and refers to the sector management information held in the sector management information holding means at the same time or before or after that. The sector management unit and the real data part of the sector are read out and stored in the sector data temporary holding means, and the real data part stored in the sector data temporary holding means is determined. Update the portion to be rewritten, update the contents of the sector management unit based on a predetermined algorithm, and update the contents of the sector management unit based on a predetermined algorithm. A data verification unit, and writes the actual data part, the sector management unit, and the data verification unit in the updated sector data temporary holding unit to the erased spare sector, and writes the sector management information in the sector management information holding unit. It is characterized by updating information.

With this configuration, sector rewriting is performed while determining a spare sector with reference to the sector management information holding means, so that even if an accident occurs during rewriting, data immediately before rewriting can be protected. . Also, since only at least one spare sector needs to be provided, the time required for rewriting can be reduced.

(3) In claim 3, when the power is turned on, the non-volatile memory control means reads out the sector management units and the data verification units of all the sectors, creates sector management information based on the information, and creates sector management information. It is characterized in that it is stored in an information storage unit.

With this configuration, it is possible to rewrite data in the nonvolatile memory thereafter without error. (4) In claim 4, the sector management unit of each sector determines the information in the sector (logical sector number) indicating the content of the data held by the sector and the number of times the data (logical sector) held by the sector has been rewritten. And information to be shown.

With this configuration, it is possible to determine which sector is a spare sector by using the number of times of rewriting of data held in each sector at the time of restart, and to generate sector management information. Can be read and written without error.

(5) In claim 5, the sector management unit of each sector rewrites information (logical sector number) in the sector indicating the contents of data held by the sector and data (logical sector) held by the sector. And rewriting order information indicating the order relationship of the time of the event.

With this configuration, it is possible to read and write data from the nonvolatile memory without error by using the order of the data rewriting time held in each sector at the time of restart.

(6) In claim 6, the sector management unit of each sector includes a sector content information (logical sector number) indicating the content of data held by the sector and an order relationship between rewriting times of all sectors. And sector rewriting order information.

With this configuration, it is possible to read and write data from the nonvolatile memory without error based on the all-sector rewrite order information at the time of restart.

(7) According to the seventh aspect, the sector management unit of each sector includes all-sector content information (logical sector number table) indicating the content of data held by each sector and the order relationship between the rewriting times of all sectors. , And all sector rewrite order information.

With this configuration, it is possible to read and write data from the non-volatile memory without error based on the order relationship between the contents information of all sectors and the time of all sectors at the time of restart.

(8) In claim 8, the data verifying section includes predetermined specific data. With this configuration, the data verification unit can detect an error in the sector data.

(9) In the ninth aspect, the data verification unit is a checksum of a sector management unit and a data unit. With this configuration, it is possible to detect an abnormality in the sector data by a simple calculation.

[0035]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing data verification and generation of sector management information according to the present invention. FIG.
The same components as 9 are denoted by the same reference numerals. In the figure, reference numeral 1 denotes a non-volatile memory, which is assigned a physical sector number and a logical sector number. 1a is an actual data part, 1b is a data verification part (checksum). 1c is a storage unit for the number of rewrites of each logical sector, 1d is a logical sector number storage unit, and 1c and 1d constitute a sector management unit. Here, a physical sector and a logical sector are used, but the physical sector is used to distinguish where to actually access, and the logical sector distinguishes where and what information is contained. It functions as management information for performing the operation.

Numeral 10 denotes sector management information holding means for indicating the correspondence between physical sectors and logical sectors, and stores sector management information indicating in which sector valid data is stored. As the sector management information holding means 10, for example, a RAM is used. Reference numeral 2 denotes a nonvolatile memory control unit, for example, a CPU, and 3 denotes a sector data temporary holding unit, for example, a RAM. Logical sector number storage 1d and logical sector rewrite frequency storage 1
c constitutes a sector management unit.

First, a start-up operation by turning on the power will be described. When power is turned on, the nonvolatile memory control means 2
Reads the sector management units and the data verification units of all the sectors, and creates an internal configuration of the sector management information holding unit 10 based on the information. The sector information (sector management unit information, data verification unit 1b) stored in the nonvolatile memory 1 is stored even when the power is turned off. Therefore, when the power is turned on, the contents can be read.

According to this embodiment, it is possible to rewrite data in the nonvolatile memory 1 thereafter without error. In the system configured as shown in FIG. 1, the nonvolatile memory control means 2
d, the number of logical sector rewrites 1c, and the checksum of the actual data portion 1a are compared, and if there is no inconsistency, the stored logical sector number is set as the logical sector number of the physical sector. However, if the same logical sector number is assigned to another physical sector, the logical sector rewrite frequency storage unit 1c is referred to as the logical sector rewrite frequency and the one with the larger logical sector rewrite frequency is made valid. The remaining physical sectors (the ones with inconsistent checksums or the smaller number of logical sector rewrites) are taken as spare sectors.

In the case shown in the figure, both physical sectors 3 and 4 have the same logical sector number 3. In this case,
The sector with the larger number of rewrites (sector having the number of rewrites 20) is used as the original sector, and the one with the smaller number of rewrites (sector having the number of rewrites 19) is used as the spare sector.

According to this embodiment, which sector is a spare sector is determined by using the number of times of rewriting of data held in each sector, and sector management information is generated, so that data from the nonvolatile memory can be read. And writing of data can be performed without error.

FIGS. 2 to 4 are explanatory diagrams of data rewriting according to the present invention. 1 are denoted by the same reference numerals. Here, a case where the contents of the logical sector 1 are rewritten will be described as an example. Non-volatile memory control means 2
Refers to the sector management information holding means 10 and copies all data of the physical sector 2 holding the logical sector 1 to the RAM 3 as shown in FIG. The spare sector at this time is the physical sector 4.

Next, the nonvolatile memory control means 2 refers to the sector management information holding means 10 to erase the physical sector 4 which is a spare sector as shown in FIG.
The data to be rewritten in M3 is rewritten and the number of logical sector rewrites is incremented by one to generate a checksum (). As a result, the number of times of rewriting in the RAM 3 changes from 12 to 13.

Next, the data in the RAM 3 is stored in the physical sector 4
And the physical sector number corresponding to the logical sector 1 in the sector management information and the physical sector number corresponding to the spare sector are replaced as shown in FIG. As a result, the logical sector 1 becomes a spare sector. At this time, the contents of the spare sector are the contents immediately before the logical sector 1.

According to this embodiment, even if an accident occurs during the processing of, it is possible to return to the state immediately before rewriting by verifying the data and generating the sector management information. Also, it is only necessary to prepare one spare sector for a plurality of sectors to be rewritten. Further, when rewriting data, it is not necessary to write the same data twice in a plurality of sectors.

In order to prevent the number of times of sector rewriting from overflowing, the area of the number of times of sector rewriting is set to be sufficiently larger than the maximum value of the assumed maximum number of times of rewriting. For example,
If the maximum number of rewrites is set to 1 million, 2 ²⁰ > 1
Since it is one million, a 20-bit area for the number of times of sector rewriting may be prepared.

Further, the magnitude relation of the number of times is cyclically considered. For example, when the area of the sector rewrite frequency is 8 bits, 0 <1 <2 <3... <255 <0, that is, 255
0 is greater than
What is necessary is just to return to 0 after 55.

The data verifying section 1b may insert the above-mentioned predetermined bit pattern instead of the checksum. In this case, if there is a predetermined bit pattern at a predetermined position of the data verification unit, it can be determined that there is no abnormality in the actual data.

FIG. 5 is an explanatory diagram of data verification and generation of sector management information according to the present invention. The same thing as FIG.
The same reference numerals are given. In the figure, reference numeral 5 denotes a total sector rewrite count storage unit for storing the total number of rewrites for all sectors. The sector rewrite count storage unit 5 is connected to the nonvolatile memory control unit 2 and stores data output from the nonvolatile memory control unit 2. Other configurations are
It is the same as FIG. The operation of the system configured as described above will be described below.

The non-volatile memory control means 2 creates sector management information while verifying the contents of the sector. That is, for each sector, the logical sector number 1d, the total number of sector rewrites 1e, and the checksum of the actual data portion 1a are compared.
If there is no inconsistency, the recorded logical sector number is used as the logical sector number of the physical sector.

However, if the same logical sector number as another physical sector is assigned, the one with the larger total number of sector rewrites is valid. The remaining physical sectors (the ones with inconsistencies in the checksum or the smaller total number of sector rewrites) are used as spare sectors.

The maximum value (20 in the physical sector 3 in the figure) of the total number of sector rewrites recorded in the sector (normal sector) having no inconsistency in the checksum is stored in the sector rewrite frequency storage unit 5 and the current sector rewrite is stored. Stored as the total number of times.

FIGS. 6 to 8 are explanatory diagrams of data rewriting according to the present invention. The same components as those in FIG. 5 are denoted by the same reference numerals. Here, a case where the contents of the logical sector 1 are rewritten will be described as an example.

In this system, referring to the sector management information, all data of the physical sector 2 holding the logical sector 1 is copied to the RAM 3 as shown in FIG. The contents of the physical sector 2 are copied to the RAM 3. At this time, the value of the sector rewrite frequency storage unit 5 is 20, which is the maximum value of the sector rewrite frequency recorded in the normal sector. The spare sector is the physical sector 4.

The nonvolatile memory control means 2 refers to the sector management information holding means 10 to erase the physical sector 4 which is a spare sector as shown in FIG. The value of the total number of rewrites storage unit 5 is incremented by 1 to 21 and the total number of rewrites is also written to the total number of sector rewrites storage unit in the RAM 3 to generate a checksum 1b ().

Next, the data in the RAM 3 is written into the physical sector 4 which is a spare sector, and the physical sector number corresponding to the logical sector 1 and the physical sector number corresponding to the spare sector in the sector management information are shown in FIG. (). Note that the content of the spare sector is the content one time before the logical sector 1.

The effects of the embodiment of the present invention are shown in FIGS.
This is the same as the embodiment shown in FIG. In order to prevent the total number of times of sector rewriting from overflowing, the area of the number of times of sector rewriting is set to be sufficiently larger than the maximum value of the assumed maximum number of times of rewriting. For example, if the maximum number of rewrites is 10
If it is set to 100,000 times, since 2 ²⁰ > 1,000,000, it is sufficient to prepare a 20-bit area for the sector rewrite frequency.

Further, the magnitude relation of the number of times is cyclically considered. For example, when the area of the sector rewrite frequency is 8 bits, 0 <1 <2 <3... <255 <0, that is, 255
0 is greater than
What is necessary is just to return to 0 after 55.

The data verifying section 1b may insert the above-mentioned predetermined bit pattern instead of the checksum. FIG. 9 is an explanatory diagram of data verification and sector management information according to the present invention. In this embodiment,
Instead of the number of times of sector rewriting, the sector management section stores the time information 1f. Time information 1f
Is composed of rewriting date and time, rewriting time, and rewriting second data. 6 is a clock.

In the system configured as described above,
The nonvolatile memory control means 2 creates sector management information while verifying the contents of the sector. That is, for each physical sector, the logical sector number 1d, the logical sector rewrite time information 1f, and the checksum of the actual data portion 1a are collated, and if there is no inconsistency, the recorded logical sector number is replaced by the logical sector number of the physical sector. And However, if the same logical sector number is assigned to another physical sector, the later sector rewrite date and time is valid. Then, the remaining physical sectors having a check sum inconsistency or the sector rewriting date and time that is earlier are set as spare sectors.

FIGS. 10 to 12 are explanatory diagrams of data rewriting according to the present invention. The same components as those in FIG. 9 are denoted by the same reference numerals. Here, a case where the contents of the logical sector 1 are rewritten will be described. Non-volatile memory control means 2
Refers to the sector management information holding means 10 and copies all the data of the physical sector 2 holding the logical sector 1 to the RAM 3 as shown in FIG. Next, the nonvolatile memory control means 2 refers to the sector management information holding means 10 and
The physical sector 4 as a spare sector is erased as shown in (b), the data to be rewritten in the RAM 3 is rewritten, the current date and time are written in the RAM 3 with reference to the clock of 6, and a checksum is further generated. Yes ().

Next, the nonvolatile memory control means 2
3 is written in the physical sector 4, and the physical sector number corresponding to the logical sector 1 in the sector management information and the physical sector number for the spare sector are replaced as shown in FIG. Note that the content of the spare sector is the content one time before the logical sector 1. The effect of this embodiment is the same as that of the above-described embodiment.

It is necessary to make the unit of the sector rewrite date and time sufficiently small so that the rewrite order can be understood. For example, if it takes at least 1 ms for one sector rewrite, the recording date and time may be recorded in units of 1 ms or less. Naturally, a clock with higher precision is required.

The data verifying section 1b may use a predetermined bit pattern instead of the checksum. As described above, according to this embodiment, data can be rewritten to the nonvolatile memory without error using the order of the data rewriting time held by each sector.

FIG. 13 is an explanatory diagram of data verification and generation of sector management information according to the present invention. The same components as those in FIG. 5 are denoted by the same reference numerals. In this embodiment,
As the sector management information, the total number of rewrites of all sectors is 1
e and a logical sector number table 1g showing the correspondence between all logical sectors and physical sectors. Other configurations are the same as those in FIG.

In the system configured as described above,
The nonvolatile memory control means 2 includes a total number 1e of sector rewrites for each sector, a logical sector table 1g,
Verify the checksum of a. Then, among the sectors whose checksums are not inconsistent (that is, normal), the largest value of the total number of sector rewrites (2 in the physical sector 3 in the figure).
0) is stored in the total sector rewrite count storage unit 5 as the current total number of sector rewrites. Then, the logical sector number table 1g stored in the sector having the largest total number of sector rewrites (the physical sector 3 in the example in the figure) is read out, and the logical sectors 0, 1, 2, 3, spare It is held as a physical sector number corresponding to each sector.

FIGS. 14 to 16 are explanatory diagrams of data rewriting according to the present invention. When rewriting the contents of the logical sector 1, as shown in FIG.
Then, referring to the sector management information, all the data of the physical sector 2 holding the logical sector 1 is copied to the RAM 3 ().

Next, the non-volatile memory control means 2 refers to the sector management information, erases the physical sector 4 which is a spare sector as shown in (b), rewrites the data to be rewritten in the RAM 3, and rewrites the sector. The number of rewrites in the total number storage unit 5 is incremented by 1 to 21 and the number of rewrites is also written in the sector rewrite total number storage unit in the RAM 3. In addition, the physical sector number corresponding to the logical sector 1 of the sector management information and the physical sector number corresponding to the spare sector are exchanged, and the physical sectors corresponding to the logical sectors 0, 1, 2, 3, and spare sector of the updated sector management information are replaced. The sector number is copied to the logical sector number table storage of the RAM 3, and a checksum is generated ().

Next, the data in the RAM 3 is written to the physical sector 4 as shown in FIG. Then, the physical sector 2 becomes a spare sector. The contents of this spare sector are
The content is one time before the logical sector 1.

The effect of the embodiment configured as described above is the same as that of the other embodiments described above. In order to prevent the total number of times of sector rewriting from overflowing, the area of the number of times of sector rewriting is set to be sufficiently larger than the maximum value of the assumed maximum number of times of rewriting. For example, if the maximum number of rewrites is set to 1,000,000, since 2 ²⁰ > 1,000,000, a 20-bit sector rewrite area may be prepared.

Further, the magnitude relation of the number of times will be considered cyclically. For example, when the area of the sector rewrite frequency is 8 bits, 0 <1 <2 <3... <255 <0, that is, 255
0 is greater than
What is necessary is just to return to 0 after 55.

The data verifying section 1b may insert the above-mentioned predetermined bit pattern instead of the checksum. Instead of the total number of times of sector rewriting, the date and time of sector rewriting may be used.

[0072]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first aspect of the present invention, a nonvolatile memory having a plurality of sectors and capable of performing electrical erasing and writing and erasing in sector units, erasing data, writing data, and writing data to the nonvolatile memory Non-volatile memory control means for instructing and controlling reading, sector data temporary holding means for temporarily holding sector data, and sector management information holding means for holding sector management information indicating in which sector valid data is stored Since sector rewriting is performed while determining a spare sector with reference to the sector management information holding means, even if an accident occurs during rewriting, data immediately before rewriting can be protected. Also, since only at least one spare sector needs to be provided, the time required for rewriting can be reduced.

(2) According to the second aspect of the present invention, sector rewriting is performed while determining a spare sector with reference to the sector management information holding means. Can be protected. Also, since only at least one spare sector needs to be provided, the time required for rewriting can be reduced.

(3) According to the third aspect of the present invention, when the power is turned on, the nonvolatile memory control means reads the sector management units and the data verification units of all the sectors, and based on the information, reads the sector management information. By making the data and storing it in the sector management information holding means, it becomes possible to read and rewrite data from the nonvolatile memory without error thereafter.

(4) According to the fourth aspect of the invention, the sector management unit of each sector includes information (logical sector number) in the sector indicating the content of the data held by the sector and the data (logical sector number) held by the sector. Information indicating the number of times a logical sector has been rewritten, and by using the number of times data has been rewritten in each sector, it is determined which sector is a spare sector, and sector management information is generated. Reading and writing of data from the nonvolatile memory can be performed without errors.

(5) According to the fifth aspect of the present invention, the sector management unit of each sector stores information (logical sector number) in the sector indicating the content of data held by the sector and data (logical sector number) held by the sector. Logical sector), the data read from the non-volatile memory and the data write can be performed by using the sequence of the data rewrite time held by each sector. It can be performed without error.

(6) According to the invention described in claim 6, the sector management section of each sector includes sector content information (logical sector number) indicating the content of the data held by the sector and the order of the rewriting time of all the sectors. By including the all-sector rewrite order information indicating the relationship, it becomes possible to read data from the nonvolatile memory and write the data without error based on the all-sector rewrite order information.

(7) According to the seventh aspect of the present invention, the sector management unit of each sector includes all sector contents information (logical sector number table) indicating the contents of data held by each sector, By including the all-sector rewrite order information indicating the order of the rewrite times, data reading from the nonvolatile memory and data writing can be performed without error based on the all-sector content information and the order of the times of all the sectors. It becomes possible.

(8) According to the eighth aspect of the present invention, the data verification unit includes predetermined specific data,
The data verification unit can detect an error in the sector data.

(9) According to the ninth aspect of the present invention, since the data verification section is a checksum of the sector management section and the data section, it can detect an abnormality in the sector data by a simple calculation. It becomes possible.

As described above, according to the present invention, even if an accident occurs during rewriting, data immediately before rewriting can be protected and the time required for rewriting data in a sector can be reduced. An apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing data verification and generation of sector management information according to the present invention.

FIG. 2 is an explanatory diagram of data rewriting according to the present invention.

FIG. 3 is an explanatory diagram of data rewriting according to the present invention.

FIG. 4 is an explanatory diagram of data rewriting according to the present invention.

FIG. 5 is an explanatory diagram of data verification and generation of sector management information according to the present invention.

FIG. 6 is an explanatory diagram of data rewriting of the present invention.

FIG. 7 is an explanatory diagram of data rewriting of the present invention.

FIG. 8 is an explanatory diagram of data rewriting of the present invention.

FIG. 9 is an explanatory diagram of data verification and generation of sector management information according to the present invention.

FIG. 10 is an explanatory diagram of data rewriting according to the present invention.

FIG. 11 is an explanatory diagram of data rewriting according to the present invention.

FIG. 12 is an explanatory diagram of data rewriting according to the present invention.

FIG. 13 is an explanatory diagram of data verification and generation of sector management information according to the present invention.

FIG. 14 is an explanatory diagram of data rewriting according to the present invention.

FIG. 15 is an explanatory diagram of data rewriting according to the present invention.

FIG. 16 is an explanatory diagram of data rewriting according to the present invention.

FIG. 17 is an operation explanatory diagram of the conventional technique 1.

FIG. 18 is an explanatory diagram of verification and restoration according to the related art 2.

FIG. 19 is an explanatory diagram of sector rewriting according to Prior Art 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-volatile memory 1a Actual data part 1b Data verification part 1c Sector rewrite frequency storage part 1d Logical sector number storage part 2 Non-volatile memory control means 3 Sector data temporary holding means 10 Sector management information holding means

Claims (9)

[Claims] 1. A nonvolatile memory having a plurality of sectors and capable of electrically erasing and writing and performing erasing in sector units, and a nonvolatile memory for instructing and controlling data erasing, data writing, and data reading in the nonvolatile memory. Memory control means; sector data temporary holding means for temporarily holding sector data; and sector management information holding means for holding sector management information indicating in which sector valid data is stored. Non-volatile memory device. 2. The non-volatile memory comprises at least one valid sector for storing valid data and at least one spare sector not storing valid data. Each valid sector and each spare sector are A non-volatile memory control means for reading out the data by referring to the sector management information held in the sector management information holding means. When determining which sector is located and reading out and rewriting data, the nonvolatile memory control means erases the spare sector and refers to the sector management information held in the sector management information holding means at the same time or before or after that. To determine in which sector the data to be rewritten is located, read the sector management section of the sector and the actual data section to temporarily store the sector data. In addition to updating the rewrite target portion of the actual data portion stored in the sector data temporary holding unit and updating the contents of the sector management unit based on a predetermined algorithm, and performing data verification based on a predetermined algorithm And writing the actual data part, the sector management part and the data verification part in the updated sector data temporary holding means to the erased spare sector and updating the sector management information in the sector management information holding means. The nonvolatile memory device according to claim 1, wherein: 3. When power is turned on, the non-volatile memory control means reads out the sector management units and data verification units of all sectors, creates sector management information based on the information, and holds the sector management information in the sector management information holding unit. 3. The non-volatile memory device according to claim 2, wherein: 4. The sector management section of each sector includes: information within a sector (logical sector number) indicating the content of data held by the sector; and information indicating the number of times data (logical sector) held by the sector has been rewritten. 4. The nonvolatile memory device according to claim 3, comprising: 5. The sector management section of each sector stores information on the contents of the data held by the sector (logical sector number) and the order of the time at which the data (logical sector) held by the sector is rewritten. 4. The nonvolatile memory device according to claim 3, further comprising rewriting order information (logical sector rewriting order). 6. The sector management unit of each sector stores sector content information (logical sector number) indicating the content of data held by the sector and all sector rewrite order information indicating an order relationship of rewrite times of all sectors. The nonvolatile memory device according to claim 3, further comprising: 7. A sector management unit for each sector, wherein: all sector content information (logical sector number table) indicating the content of data held by each sector; The nonvolatile memory device according to claim 3, further comprising information. 8. The nonvolatile memory device according to claim 1, wherein said data verification unit includes predetermined specific data. 9. The data verification unit according to claim 1, wherein the data verification unit is a checksum of a sector management unit and a data unit.
8. The nonvolatile memory device according to any one of claims 1 to 7.